1. Field of the Invention
The invention concerns a transportable circular table saw with an exterior housing having a tabletop forming a workpiece support surface, a sawing unit being arranged in the exterior housing underneath the tabletop with a drive motor and a circular saw blade protruding into the tabletop from below through a saw slot, the sawing unit being slidable in respect of the tabletop in a pulling direction, as a result of which the circular saw blade moves in the saw slot in the pulling direction. The teaching of the present invention thus deals with transportable machines but not with handheld machines.
2. Description of Related Art
There are various types of circular saws in the field of stationary wood working machines (or metal working machines which are also considered here, without this being expressly stated from now on).
A complete program for wood working machines has been provided by the applicant (applicant""s brochure xe2x80x9cwood working machinesxe2x80x9d 10/94-EB-F-100.000/093 301 2131). It includes circular table saws as builder""s circular saws where only the height of the circular saw blade is adjustable. A further embodiment of a circular table saw not only comprises a height-adjustable sawing unit, but also comprises adjustment for both the height and the lateral inclination at least to one side, either infinitely or in steps (circular table saw TKHS, pages 30 ff. as well as precision circular saw PK 300 K, pages 24 ff. of the applicant""s brochure). Mitre cuts in one cutting plane are possible with a circular table saw whose sawing unit can be inclined to one side in respect of the axis of the mitre cut. Bevel mitre cuts or compound cuts can only be made by aligning the workpiece at the desired angle on the workpiece support surfaces on angle stops.
An underbench circular crosscut saw (e.g., underbench circular crosscut saw UK 330, pages 16 ff. of the applicant""s brochure) is a further improved circular table saw. With an underbench circular crosscut saw, the sawing unit is not only adjustable in height, and laterally inclinable in respect of the axis of the mitre cut, but the sawing unit can additionally be pulled, from the rearmost position right to the front, in the saw slot of the tabletop. In this way, the length of the cut becomes significantly longer; a workpiece can be fixed and can remain resting on the workpiece support surface while the circular saw blade is being pulled through the workpiece.
The teaching of the present invention is based on an underbench circular crosscut saw (published European Patent Application EP-A-0 615 807). With an underbench circular crosscut saw, beveled mitre cuts can also only be produced by shifting the workpiece. If one wishes to cut a workpiece with an angle in the plane of the workpiece support surface, then here too, the workpiece must be aligned on angle stops in the desired angle position in respect of the circular saw blade.
A cross-cut saw and mitre-cut saw (e.g. KGS 330, pages 6 ff. of the applicant""s brochure) has the advantage that beveled mitre cuts can be made without shifting the workpiece. In this saw, the sawing unit is arranged at the top of the tabletop. To carry out cross-cuts, the sawing unit can be hinged down onto the workpiece support surface of the tabletop, by a horizontal hinging axis. If the sawing unit can be pulled on draw rods, larger lengths of cuts can be achieved. Here too, a first axis of the mitre cut is horizontal approximately in the plane of the workpiece support surface. However the tabletop is additionally rotatable to some extent in the exterior housing or in a surrounding top, on a vertical axis perpendicular to the workpiece support surface, with rotation usually being xc2x145 degrees. The vertical axis represents the second axis of the mitre cut. In this way, mitre cuts in two cutting planes perpendicular to each other, i.e., beveled mitre cuts, can be carried out.
A cross-cut and mitre-cut saw regularly has the disadvantage that very large workpieces cannot be cut because the length of the cut is insufficient. Because the sawing unit is arranged above the tabletop, a large boards shaped workpiece cannot be pushed past the circular saw blade.
A cross-cut, mitre and circular table saw (for example, KGT 550, pages 14 ff. of the applicant""s brochure) combines the advantages of a circular table saw with the advantages of a cross-cut and mitre-cut saw. In a cross-cut, mitre and circular table saw, th e tabletop is arranged in the exterior housing so as to be reversible by 180xc2x0. The sawing unit is attached on one side of the tabletop. If the tabletop is positioned with the saw unit on the top, the saw can be used as a cross-cut saw and mitre-cut saw. For this purpose, the tabletop itself is arranged in the surrounding top so as to be reversible. In the table saw position, the saw unit is located underneath the tabletop and fixed in a table saw position so that the circular saw protrudes from below through the saw slot. In this position, the tabletop cannot be rotated on its vertical axis; the circular table saw has its usual function. Since the sawing unit is not slidable, the length of the cut in the cross-cut saw is limited by the diameter of the saw blade.
Positioning the workpiece on the workpiece support surface to achieve mitre cuts in the cutting axis or beveled mitre cuts is problematical especially where space is limited. If for example such a saw unit is located in a corridor, there is essentially only one possible alignment for long workpieces. If at all possible, alignment of the circular saw blade in respect of the workpiece should be achievable by changing the position of the circular saw blade and not the workpiece.
An attempt to address the problems shown above has already been made with a saw which is integrated into an elongated workbench (U.S. Pat. No. 2,513,873). Here, the elongated workbench is standing on four fold-out legs. At the right extremity of the elongated workbench, a rotatable tabletop is held on sliding bearings or ball bearings in said elongated workbench. A sawing unit with a circular saw blade is arranged below the tabletop. The said saw unit can be moved in a pulling direction in respect of the tabletop, causing the circular saw blade to move in the pulling direction in a saw slot which extends along a large part of the length of the tabletop. Since the sawing unit on the right is located in a part of the work table which juts out, the tabletop with the sawing unit hanging below, which sawing unit is slidable in the pulling direction, can be rotated on the axis perpendicular to the workpiece support surface.
It is the object of the invention to improve the known transportable circular table saw of the type explained in the introduction, to the extent that in any case, beveled mitre cuts can be made on it without the need for the workpiece having to be repositioned.
This object is met in a transportable circular table saw with an exterior housing having a tabletop forming a workpiece support surface, a sawing unit being arranged in the exterior housing underneath the tabletop with a drive motor and a circular saw blade protruding into the tabletop from below through a saw slot, the sawing unit being slidable in respect of the tabletop in a pulling direction, as a result of which the circular saw blade moves in the saw slot in the pulling direction. The teaching of the present invention thus deals with transportable machines but not with handheld machines by the housing having a horizontal U-shape having a recess extending from the front face towards the rear and extending across the entire width of the exterior of the housing underneath the tabletop.
According to the invention, the exterior housing of the transportable circular table saw, which in plane view is approximately square in shape, comprises a non-reversible tabletop. This tabletop is however rotatable on a vertical axis aligned perpendicular to the workpiece support surface, in this case held in the surrounding top of the exterior housing. The saw unit is rotatable in the vertical axis together with the tabletop.
Due to the rotation of the tabletop, the circular saw table according to the invention also makes it possible to carry out angular cross cuts and beveled mitre cuts as well as longitudinal cuts in workpieces (at an angle setting of 90xc2x0), without the angular position of the workpiece on the workpiece support surface having to be changed. As a positive consequence of this, the circular saw table according to the invention, with any widening or lengthening attachments, can also be used in confined spaces, in particular in narrow halls and corridors.
The concept of the transportable circular table saw according to the invention only becomes possible in that in side view the circular table saw is U-shaped. The control element for freely rotating the tabletop to the right and/or left can be accommodated in the recess created in this way; said recess extending from the front across the entire width of the exterior housing underneath the tabletop.
Below, the invention is explained in more detail with reference to the accompanying drawings.